President Michael D. Higgins makes his country’s first state visit to Britain since Ireland’s hard-fought independence nearly a century ago.

Britain's Queen Elizabeth hosts a banquet for Ireland's President as the first Irish head of state to visit. Paul Chapman reports.

Peter Macdiarmid
/ GETTY IMAGES

The Queen talks with Ireland's president, Michael D. Higgins, during a ceremonial welcome at Windsor Castle on April 8. This is the first official visit by the head of state of the Irish Republic to the United Kingdom.

LONDON—Amid regal pomp at Windsor Castle and thunderous applause from British lawmakers, Ireland’s president began a state visit laden with symbolism for two nations that share a troubled history.

President Michael D. Higgins is making his country’s first state visit to Britain since Ireland’s hard-fought independence nearly a century ago. His trip underscores how much Northern Ireland’s peace process has transformed relations between the two longtime adversaries since the 1990s, when IRA car bombs were still detonating in London.

Higgins, delivering the first speech by an Irish president to the joint Houses of Parliament, said Tuesday that both nations had attained “a closeness and warmth that once seemed unachievable.”

Previous Irish presidents had toured England and met the Queen in several official trips since 1993 as part of early peacemaking efforts. But a formal state visit with full honours had been repeatedly postponed because of security and diplomatic sensitivities.

Higgins, a left-wing politician, poet and human rights activist who was elected to the ceremonial post in 2011, said the two nations’ relationship had gone “from the doubting eyes of estrangement to the trusting eyes of partnership and, in recent years, to the welcoming eyes of friendship.”

“Our two countries can take immense pride in the progress of the cause of peace in Northern Ireland,” he said. “There is, of course, still a road to be travelled, the road of a lasting and creative reconciliation.”

Earlier, a military band played Ireland’s martial national anthem, “The Soldier’s Song,” as the Queen and Prince Philip welcomed Higgins and his wife, Sabina, into the castle quadrangle. Outside, Irish tricolours and Union Jacks lined the streets of Windsor for the start of Higgins’ four-day tour of England.

The most striking symbolism was coming later Tuesday at a Windsor Castle banquet hosted by the Queen.

Among the 160 invited guests was Martin McGuinness, once a senior Irish Republican Army commander, now deputy leader of Northern Ireland’s unity government. His presence at the Queen’s table would have been unthinkable even a few years ago.

More than 3,600 people were killed during the four-decade conflict over Northern Ireland. The main faction of the IRA killed nearly 1,800 people — among them the Queen’s cousin, Lord Louis Mountbatten — during its failed effort to force Northern Ireland out of the United Kingdom. Experts say McGuinness was the IRA’s chief of staff when the group assassinated Mountbatten in 1979.

Another 1,000 people were killed by Protestant militants and about 360 by British security forces.